def main():
    import sys
    input = sys.stdin.read().split()
    ptr = 0
    N = int(input[ptr])
    ptr += 1
    M = int(input[ptr])
    ptr += 1

    post_x = []
    destinations = []

    for _ in range(M):
        x = int(input[ptr])
        ptr += 1
        d = int(input[ptr])
        ptr += 1
        post_x.append(x)
        for __ in range(d):
            y = int(input[ptr])
            ptr += 1
            destinations.append(y)
    
    if not post_x:
        p_min = p_max = 0
    else:
        p_min = min(post_x)
        p_max = max(post_x)
    
    if not destinations:
        d_min = d_max = 0
    else:
        d_min = min(destinations)
        d_max = max(destinations)
    
    # Calculate the four components
    part1 = p_max - p_min
    part2 = d_max - d_min
    part3 = max(0, p_max - d_max)
    part4 = max(0, d_min - p_min)
    total = part1 + part2 + part3 + part4
    print(total)

if __name__ == '__main__':
    main()